Field of the Invention
This invention relates to a method for warping with a cone sectional warper that winds up threads in bands on a warping drum, in which a support for a thread guide comb and the warping drum are shifted in parallel relative to one another corresponding to the growing wind thickness and predetermined warping data, with the first band being scanned during a measurement phase by a roll pressed against it, and the scanned displacement path is recorded as a function of the number of rotations of the warping drum and with the pressure of the roll on the wind being monitored by continuous measurement during the measurement phase, and particularly in case of a deviation of the monitored result from a predetermined setpoint, with a correction being made in the advance of the support according to Patent . . . (Patent Application 196 46 087.5-26).
Warping consists of winding up warp threads in bands. The winding is accomplished by rotation of the warping drum. The first band and with it all of the following bands supported on it are given a parallelogram cross section by the special shape of the warping drum, namely its conicity. The speed of rotation and the forward advance of the warping drum are determined by item-specific data for the threads, such as their diameter or the number and type of capillaries. Different winding speeds and thread tension forces and/or roll pressure applied cause different buildups of the wind. This is manifested, for example, in support differing in strength for soft or hard winding for the next band.
The underlying purpose of the principal Application is to be able to exert an effect on the wind buildup to provide for immediate detection and elimination of irregularities.
This problem of the principal Application is solved by continuously monitoring by measurement the pressure of the roll on the wind during the measurement phase and/or during the further winding and/or copying, and if there is a deviation of the monitored result from a predetermined setpoint, by making a correction of the support advance feed.
The method is essentially carried out by placing a roll on the wound-up band and supporting it on two pressure sensors, whose measurements can be utilized by the control device. The pressure sensors can detect both excessive and inadequate pressures. If the measured pressure differs too greatly from the mean value or setpoint, the warping data can be corrected. Great unevenness or pressure variations that are difficult to correct arise from thickening of the band because the thread array is knotted in the tying strip of the warping drum at the beginning. Winding over the knots also leads to severe unevenness when the tie points are recessed in the conical drum. This can lead to measurement errors or damage to the threads of the band during scanning by the roll. The measured pressure changes may also be very large, so that they are outside a measurement range by a given average and can thus lead to control problems. For example, it is then necessary to smooth out pressure peaks. The problem of the present invention therefore consists of improving the method described initially so that no irregularities in the pressure contact of the roll occur during the initial rotations after hanging the band, and thus any damage to the roll or to the threads is prevented.
The aforementioned problem is solved by positioning the roll at a predetermined distance from the warping drum at the beginning of the warping of the first band, and by starting the measurement phase automatically with growing wind thickness as soon as the wind sets the roll in rotation.
Such a method causes the warped band to contact the measurement roll only in a later stage of the warping process. Only when the band reaches a thickness that conforms to the predetermined distance is the band scanned by the roll. The distance is preset so that the substantial unevenness from the hanging knots and other factors involving the beginning of warping no longer have any effect on the result of measurement. The initial unevenness and any pressure variations have no effect in the method described. The measurement device provided can be used from then on without adjusting for pressure peaks and does not have to be reprogrammed.
DE-OS 37 02 293 discloses a method for warping with a warping drum, in which winding is done with a preset warping carriage advance feed and the base winding produced is scanned with a scanning element. A corrected warp carriage advance is used corresponding to the scanning result. This method is to be used to exclude the influence of the hard warping drum backing and other factors associated with the beginning of warping from the measurement process. To scan the wind circumference with the scanning element, the warping drum has to be stopped. This stopping, scanning, and correction of the advance makes the measuring and warping process substantially more difficult. Furthermore, there is the danger that a stepped wind will be formed by stopping the warping drum and subsequently restarting it.
The warping method pursuant to the invention can be carried out by shifting the support only parallel to the warping drum and with a support advance feed adjusted for the thread data before starting the measurement phase. The thread data, for example, are the thickness and density of the thread. The support feed adjusted for this, combined with the motion of the support made parallel to the warping drum, brings about the winding of a partial band with parallelogram cross section tuned to the conicity of the warping drum even before starting the phase of measurement by the roll.
The warping method can be carried out so that the measurement phase starts automatically with a measured pulse emitted by the rotating roll. This provides for the measurement phase to be started only when the roll is rotating. It is guaranteed that a wind with spacing conforming to the predetermined distance is built up. The control mechanism is addressed by tapping the measurement pulse and the measurement phase is automatically started. It is not necessary to interrupt the warping process. No time is lost by interrupting, and the danger of stepwise winding is avoided.
It is advantageous to carry out the warping method by tapping the measurement pulse as soon as the measurement roll is set in motion. A very early phase of the motion is utilized as the starting point of measurements. It is not necessary for the roll to execute a full rotation, but for example half a rotation or even less is sufficient. This makes possible the use of a simple detector, i.e. a speed-independent detector, to record the motion, for example a proximity sensor with a simple aperture.
It may also be advantageous to carry out the method with the measurement pulse being tapped as soon as the speed of rotation of the roll has reached a given value. This avoids unforeseen random rotations of the roll from any contact or vibrations being interpreted as the start for the measurement process. The setting and measurement of the speed of rotation make possible a more reliable determination of actual contact of the roll with the wind. For example, the measurement pulse can be tapped when the speed of rotation of the roll at its outer circumference has reached half of the winding speed of the wind, or half the circumferential speed of the wind.
It may be advantageous in the method for warping with a cone sectional warper in which threads are wound in bands on a warping drum, to retract the roll after the measurement phase during the further winding corresponding to an average value obtained in the measurement phase, and to press it against the wind and continuously to monitor the pressure of the roll during the further winding and/or copying by measurement, and in case of a deviation of the result of monitoring from a predetermined setpoint, to make a correction to the support advance feed. This provides the ability to have a corresponding influence on the wind buildup. A check is made during the copying of the first band as to whether the wind buildup is correct, for example in case of problems from the increase of thread tension resulting from decreasing thread supply of the bobbins, or from a multiplication effect from inexact input parameters. Complete regulation of the pressure of the roll is thus possible during the entire wind buildup.
It is advantageous to carry out the method by positioning the roll with the same predetermined distance from the warping drum also at the beginning of the warping of the other bands, and to warp with the same warping data as for the first band until the measurement phase is reached. The predetermined distance of the roll in turn makes it possible easily and reliably to avoid irregularities when applying pressure to the roll during the first rotations after hanging the band. The choice of the same warping data until the measurement phase is reached guarantees the same type of winding and a corresponding length of the next band and the following bands. It is not necessary to scan the wind with the roll.
It is also advantageous to design the method so that the wind buildup of the first band starting with the measurement phase is copied when warping the other bands. This guarantees exactly the same buildup of the first band and the following bands. The supporting action of the bands is always the same because of this, and no irregularities of bands or different warp lengths are obtained.
The invention relates to a cone sectional warping machine with a support carrying a thread guide comb, which is adjustable on a machine frame parallel to a warping drum, with a motorized advance drive controllable by a control device to produce relative motions corresponding to the increase of the wind thickness between the warping drum and the support, with a roll scanning the circumference of the wind with pressure, whose displacement can be stored by the control device as a function of the number of rotations of the warping drum and that is supported on at least one pressure sensor that activates the control device during the measurement phase, with the control device controlling the roll in the corrective direction in case the measured pressure differs from a predetermined setpoint.
The cone sectional warping machine described above can be improved in the sense of avoiding irregularities in the pressure contact of the roll during the first rotations after hanging the band by providing a stop with which the roll is positioned at a distance from the warping drum during warping until a predetermined wind thickness of the band is reached. This provides for simple adjustment of the roll before warping and reliable positioning during the beginning of the warping process. No pressure variations are passed along to the control device. Any vibrations from startup and from the first rotations of the warping drum have no effect, because the measurement phase has not yet started.
The cone sectional warping machine can be designed by providing a pulse generator that emits a pulse to start the measurement phase with a predetermined speed of rotation of the roll. The pulse generator, preferably located near the roll, causes the rotation of the roll to be recorded and brings about simple starting of the measurement phase. It is adjustable independently of the control device, which contributes to a more exact measurement.
The stop is present on the support, so that it can always be used in the same way when shifting the support to warp the following bands, and a constant distance of the roll is always guaranteed. The roll can be held against the stop without pressure.